Computed tomography (CT) has been widely used in clinical diagnosis and made a great contribution to diagnosis by providing anatomical information with high-resolution.However,when metal implants exist in patients' body,reconstructed CT images are seriously interfered by metal artifacts.Metal artifacts are usually expressed as many dark and bright radiant streak artifacts which seriously reduce diagnosis reliability and bring errors into the calculation of dose distribution in radiotherapy.Therefore,the study of metal artifact reduction (MAR)is of great importance.This article reviews main methods on MAR developed in recent years,and give deep analysis on some of the methods.

Objective To study the relationship between the level of uric acid and oxidative stress in patients with chronic systolic heart failure (CSHF). Methods One hundred and nine hospitalized patients from June 2006 to March 2007 were selected. Based on organic heart disease and heart function, they were classified into two groups: CSHF group (81 cases) and control group (28 eases). According to NYHA heart function grade (Ⅱ, Ⅲ, Ⅳ), CSHF group was divided into three subgroups. The plasma concentration of GSH and GSSG was determined by using glutathione reduetase recycling method (GR-DTNB). Redox potential (Eh) was calculated using Nemst equation according to the concentration of reduced and oxidized glutathione. Results There was significant difference between control group and CSHF group in the level of uric acid [(310.54±99.92) μ mol/L vs (499.09±168.04) μ mol/L], P < 0.01. Uric acid had a negative correlation with LVEF (r=-0.247, P=0.026), and a positive correlation with LVED D (r=0.266, P=0.016). The concentration of uric acid had a negative correlation with GSH (r=-0.328,P=0.003), and a positive correlation with GSSG (r=0.244, P=0.028) and Eh (r=0.309, P=0.005). Conclusions The concentration of uric acid increases in CSHF patients and has a correlation with LVEF and LVEDD. It may be a supplementary marker to reflect heart function and the serious degree of CSHF. The concentration of uric acid has a negative correlation with GSH, and a positive correlation with GSSG and the value of Eh. It may be used as an indicator of oxidative stress concerning its metabolic pathway.

Nicotinamide phosphoribosyltransferase (NAMPT) is the rate-limiting enzyme in the salvage pathway for the biosynthesis of nicotinamide adenine dinucleotide (NAD+) from nicotinamide. NAMPT is also a cytokine that inhibits the apoptosis of neutrophils under various inlfammatory stimuli, regulates various diseases and closely associates with the progression and prognosis of cancers. However, it is still not clear whether the cytokine-like function of NAMPT is interrelated with the biosynthesis enzyme activity of NAD+. This article aims to provide novel insights for inflammation and cancers treatment by reviewing the function of NAMPT in inflammation, carcinogenesis, cancer progression and its inhibitors, APO866/FK866.

Intensity-modulated radiation therapy is widely used in the treatment of tumor,and the dose distribution highly conforms to tumor target area in three-dimension.However,the factors such as complex beam,data error,algorithm error and machine error may cause large dose deviation in intensity-modulated radiation therapy,which may lead to unnecessary radiation accident.Therefore,standing on the patients' safety point of view,dose verification is usually performed before executing the treatment plan in order to ensure the safe implementation of the treatment plan and to avoid un-planned irradiation dose.Currently,there are many tools and methods of dose verification in clinic,including point dose verification tools like finger-shaped ionization chamber and thermoluminescence dosimeter;two-dimensional dose verification tools like Mapcheck,MatriXX and films;three-dimensional dose verification tools like ArcCHECK,Delta4 and the third-party software.These common clinical dose verification methods are reviewed in this paper.

Objective To study the detective sensitivity for position of multi-leave collimators ( MLC) using Delta-4. Methods First,the small positional deviation of MLC was simulated and measured using the linac (Varian,Trubeam) equipped with EPID.Then,two beam fields 2. 0 cm (x)×6. 0 cm (y), 7. 0 cm (x)×6. 0 cm (y) were designed,the x1 and x2 of MLC were expanded 0. 1 mm,0. 2 mm,0. 3 mm... 0. 9 mm and 1. 0 mm,2. 0...5. 0 mm to external simultaneously,different parameters of 3 mm/3%,2. 5 mm/2. 5%,2 mm/2%, 1. 5 mm/1. 5% and 1 mm/1% were used in Gamma analysis to analyze the difference between dose distribution detected by Delta-4 and original dose distribution with unexpanded MLC position derived from TPS. Results For 2. 0 cm ( x) × 6. 0 cm ( y) beam field, the pass rate of original dose distribution was 100%,and that decreased to 95. 5% when x1 ,x2 of MLC were expanded 0. 3 mm to external, and decreased to 89. 4% when expanded 0. 5 mm at 2. 5 mm/2. 5% statistical standards. For 7. 0 cm ( x) × 6. 0 cm ( y) beam field,the pass rate of original dose distribution was 96. 5%,and that decreased to less than 95% when x2,x2 of MLC were expanded 0. 3 mm to external,and passing rate was above 90% when MLC expanded less than 0. 5 mm at 1. 5 mm/1. 5% statistical standards. Conclusions For MLC' s positional deviation in decimillimeter level,raise standards of Gamma analysis properly may improve the capability of Delta-4 for detecting small positional deviation,but it won' t detect all the positional deviation of MLC in decimillimeter level. For different size of beam field,it is proposed to use different analytical standards for Delta-4.

Antiviral Agents ; therapeutic use ; Female ; Hepatitis B, Chronic ; drug therapy ; Humans ; Pregnancy ; Pregnancy Complications, Infectious ; drug therapy ; virology

More and more patients were treated by surgery with metal implants in clinic.Metal artifacts in CT images caused by metal implants brought challenges for postoperative evaluation and diagnosis of tumor.It also led to the possibility of missed diagnosis and misdiagnosis.In recent decades,the improved methods based on filtered-backprojection and iterative reconstruction algorithms have great progresses in reducing effects of metal artifacts.The actuality of techniques for metal artifact reduction were reviewed in this article.

With the improvement of the complexity of medical image synthesis and the demand for the accuracy of clinical radiotherapy, deep learning algorithm plays an increasingly important role in pseudo CT image synthesis and analysis. This paper classifies and analyzes the pseudo CT image synthesis technology based on deep learning method in terms of the types of image modes, and describes the ongoing application in radiotherapy.

Objective To study the percentage depth dose difference (PDD) between Monte Carlo method and the measurement method.Methods Based on the detail treatment head structure designing by the manufacture,the BEAMnrc Monte Carlo code was used to simulate the 6 MV photon beams of a Siemens Primus linear accelerator.DOSXYZnrc program generated 6 MV X-ray parameters such as PDD,and it was measured by MP3 three-dimensional water of PTW corporation phantom.The deviation of PDD was calculated using formulas ((measured value-simulation algorithm value)/measured value × 100％).Results Distance from the surface of the water was less than 1.2 cm,the deviation of PDD was ＞ 2％.Distance from the surface greater than 1.2 cm,the deviation of PDD was ＜ 2％.Conclusion In the built-up areas,PDD obtained by the Monte Carlo simulation algorithm is more accurate.

In Chongqing Medical University,Introduction to Clinical Medicinewas first launched in 2002. In this article, based on the summary of 2014 to 2015, we summarized respectively from teaching material construction, evaluation system with combination of formative assessment and summative assess-ment, network support platform, teaching quality monitoring system, and student questionnaire survey and evaluation. Through the study of the course, 99.5% (836/840) of the students think their team conscious-ness and cooperation ability were improved, 94.2% (791/840) of the students consider this course can im-prove their innovative ability of self-learning, 87.0% (731/840) of the students think it is beneficial to the improvement of their self expression ability and more than 78.0% of the students think they have achieved the goal of early clinical contact, expanding knowledge, and enhancing the basic professional quality.